Many manufacturing processes produce granular or particulate products where either one or more of the properties of moisture content, temperature, density, and flow rate are important to the process or to the finished product. By way of example only and not limitation, some of these processes include:
1. Drying or cooling of grain, pelleted or extruded feeds, or extruded human foods.
2. Controlling the application of heat sensitive ingredients to cooled feeds/foods including such things as enzymes, vitamins, and other heat sensitive materials.
3. Drying or cooling of pelleted byproducts made from peat, sawdust, corn gluten or the like.
4. Monitoring and controlling moisture content of sand in concrete mixing.
5. Monitoring moisture content of pulverized coal at electric power generating plants.
6. Monitoring and controlling moisture content of ingredients entering food or feed manufacturing processes.
It is desirable to monitor the particular material property or properties that are important to the particular process or finished product. It is convenient to monitor these properties xe2x80x9con linexe2x80x9d or when the material is being conveyed from one location to another, either as part of the process or expressly for the purpose of monitoring a property. Without good on line information about a product or process, automation and quality control are difficult. However, current choices of equipment for monitoring these parameters on-line are very limited or very expensive.
The invention pertains to a device for use in on-line monitoring of one or more properties of a moving stream of particulate material. The material may be moving by means of a mechanical conveyor such as a conveyor belt or under the influence of gravity, such as in an inclined chute. The monitoring device includes a sled that rides on top of the stream of moving material. In its most essential form the monitoring device includes a sled and a mounting structure. The mounting structure mounts the sled in stationary relationship to the stream of particulate material. However, the mounting structure permits the sled to xe2x80x9cfloatxe2x80x9d on the surface of the moving particulate stream, The sled can move up and down on the top of the stream, or in a direction that is substantially perpendicular to the direction of movement of the stream of material.
The sled has a base with a substantially flat bottom or under surface to skim over the surface of the particle stream in sled-like fashion. The sled has an upwardly sloped upstream edge or bow that faces the oncoming flow of particulate material. This permits the sled to ride on the top surface of the particle stream with minimal drag.
In a defined channel, the elevation of the sled above the lower surface of the process stream is a measure of the depth of the stream. In combination with the velocity of the particle stream, this is proportional to the flow rate. A measurement device can measure this depth dimension. The device can be remote from the sled and mounting structure, such as a remotely located optical measuring device. The device can be on board the sled or the mounting structure. The device can measure the vertical displacement of the sled, or the angular displacement of a mounting rod connecting the sled to the mounting structure.
The sled can carry on board measurement devices to measure other properties of the particle stream such as temperature and moisture content. A particular sensor can sense dielectric properties of the process stream which will be indicative of the moisture content and density. The linear velocity of the particle stream can be measured permitting a computation of the mass flow rate.
The device can include a flume-like collector to produce a defined process stream channel. The collector includes parallel sidewalls straddling the sled in forming a collector cell. Flow deflectors extend from the upstream edges of the parallel sidewalls in a divergent relationship. The flow deflectors form a funnel-like structure to direct the process stream into the sampling cell. A leveling device can be used to level the surface of the process stream prior to passing under the sled.